Teams ranked 25-75 beat top 10 teams pretty frequently in basketball. Its far more rare for a team outside the top 25 to beat a top 10 team in football. (and I'm speaking about the rankings towards the end of the season, once the true team quality levels have been determined.) Not only is basketball a sport where team performances fluctuate from game to game more than they do in football, but the talent levels are much more evenly distributed. Football has 22 starters on offense and defense, and 80 scholarship limits. Basketball has 5 starters and 13 scholarships per team, so the talent trickles down better within the top 75 basketball teams in contrast to football where the top talent concentrates heavily to a handful of teams.